Bronchoconstrictive disorders affect millions worldwide. Such disorders include asthma (including bronchial asthma, allergic asthma and intrinsic asthma, e.g., late asthma and airway hyper-responsiveness), chronic bronchitis and other chronic obstructive pulmonary diseases. Compounds having β2-adrenoreceptor agonist activity have been developed to treat these conditions. Such compounds include, but are not limited to, Albuterol (α1-(((1,1-dimethylethyl)amino)methyl)-4-hydroxy-1,3-benzenedimethanol); Bambuterol (dimethylcarbamic acid 5-(2-((1,1-dimethylethyl)amino)-1-hydroxyethyl)-1,3-phenylene ester); Bitolterol (4-methylbenzoic acid 4-(2-((1,1-dimethylethyl)amino)-1-hydroxyethyl)-1,2-phenylene ester); Broxaterol (3-bromo-α-(((1,1-dimethylethyl)amino)methyl)-5-isoxazolemethanol); Isoproterenol (4-(1-hydroxy-2-((1-methyl-ethyl)amino)ethyl)-1,2-benzenediol); Trimetoquinol (1,2,3,4-tetrahydro-1-((3,4,5-trimethoxyphenyl)methyl)-6,7-isoquinolinediol); Clenbuterol (4-amino-3,5-dichloro-α-(((1,1-diemthylethyl)amino)methyl)benzenemethanol); Fenoterol (5-(1-hydroxy-2-((2-(4-hydroxyphenyl)-1-methylethyl)amino)ethyl)-1,3-benzenediol); Formoterol (2-hydroxy-5-((1RS)-1-hydroxy-2-(((1RS)-2-(p-methoxyphenyl)-1-methylethyl)amino)ethyl)formanilide); (R,R)-Formoterol; Desformoterol ((R,R) or (S,S)-3-amino-4-hydroxy-α-(((2-(4-methoxyphenyl)-1-methylethyl)amino)methyl)benzenemethanol); Hexoprenaline (4,4′-(1,6-hexanediyl)-bis(imino(1-hydroxy-2,1-ethanediyl)))bis-1,2-benzenediol); Isoetharine (4-(1-hydroxy-2-((1-methylethyl)amino)butyl)-1,2-benzenediol); Isoprenaline (4-(1-hydroxy-2-((1-methylethyl)amino)ethyl)-1,2-benzenediol); Metaproterenol (5-(1-hydroxy-2-((1-methylethyl)amino)ethyl)-1,3-benzenediol); Picumeterol (4-amino-3,5-dichloro-α-(((6-(2-(2-pyridinyl)ethoxy)hexyl)amino)methyl)benzenemethanol); Pirbuterol (α6-(((1,1-dimethylethyl)amino)methyl)-3-hydroxy-2,6-pyridine-methanol); Procaterol (((R*,S*)-(±)-8-hydroxy-5-(1-hydroxy-2-((1-methylethyl)amino)butyl)-2(1H)-quinolinone); Reproterol ((7-(3-((2-(3,5-dihydroxyphenyl)-2-hydroxyethyl)amino)propyl)-3,7-dihydro-1,3-dimethyl-1H-purine-2,6-dione); Rimiterol (4-(hydroxy-2-piperidinylmethyl)-1,2-benzenediol); Salbutamol ((±)-α1-(((1,1-dimethylethyl)amino)methyl)-4-hydroxy-1,3-benzenedimethanol); (R)-Salbutamol; Salmeterol ((±)-4-hydroxy-α1-(((6-(4-phenylbutoxy)hexyl)amino)methyl)-1,3-benzenedimethanol); (R)-Salmeterol; Terbutaline (5-(2-((1,1-dimethylethyl)amino)-1-hydroxyethyl)-1,3-benzenediol); Tulobuterol (2-chloro-α-(((1,1-dimethyl-ethyl)amino)methyl)benzenemethanol); and TA-2005 (8-hydroxy-5-((1R)-1-hydroxy-2-(N-((1R)-2-(4-methoxyphenyl)-1-methylethyl)amino)ethyl)carbostyril hydrochloride).
These compounds are typically formulated for inhalation therapy. Aqueous or liquid formulations are preferred over formulations of solids. Powdered formulations are more difficult to administer, particularly to the young and elderly who are most often the patients in need of such therapy. Compounds, such as formoterol, which has many desirable properties, are not adequately stable in aqueous solutions to be formulated as liquids. Hence there is a need for formulations of compounds, such as formoterol, in a form that can be conveniently administered.
Other prophylactic therapeutics for use in treatment of bronchoconstrictive disorders include steroidal anti-inflammatory agents such as beclomethasbne dipropionate (BDP), beclomethasone monopropionate (BMP), flunisolide, triamcenolone acetonide, dexamethasone, tipredane, ciclesonid, mometasone, mometasone furoate (Asmanex® Twisthaler™, Shering-Plough Corporation, Kenilworth, N.J.), RPR 106541, fluticasone, fluticasone propionate and budesonide. These agents can be formulated for inhalation therapy.
Effective treatment of asthma and other bronchoconstrictive disorders often requires combination therapy. It is advantageous to administer combinations of bronchodilators and other agents, such as anti-steroidal agents. Since some the β2-adrenoreceptor agonist compounds are not available as aqueous or liquid formulations, combinations thereof with other agents, are not available as aqueous or liquid formulations. Since aqueous or liquid formulations are preferred, there is need to develop liquid formulations. Therefore, it is an object herein to provide stable liquid formulations of β2-adrenoreceptor agonist compounds. It is a further object herein to improve the stability of existing liquid formulations.